Can't? Cat got your tongue? Then you might have some idea of the unmitigated disaster that is Little Miss Sunshine, playing through March 27 in the Mandell Weiss Theatre on the La Jolla Playhouse campus.

The 2006 road-trip film of the same name was one of the biggest indie hits ever, and it attracted four Academy Award nominations, including Best Picture. It won two Oscars, one for Michael Arndt's quirky but ultimately affirming screenplay, and a second for Alan Arkin's hilariously rude performance as Grandpa.

In the La Jolla production, James Lapine adapted Mr. Arndt's screenplay (and directs), keeping the story but taking out much of the wackiness. And veteran performer Dick Latessa does, indeed, walk off with the show as Grandpa. Unfortunately, when Grandpa dies all hope for the show dies with him.

In case you never managed to see the film, its story concerns a family living above its means and trying a variety of schemes to make the income match the lifestyle. Richard Hoover (Hunter Foster) has a get-rich-quick plan to set himself up as a motivational speaker and trainer. Eternally optimistic, he preaches persistence and a positive attitude, qualities that are seriously challenged when the family decides to drive daughter Olive (Georgi James) from Albuquerque to Redondo Beach to compete in the Little Miss Sunshine child beauty pageant. The riders who load up the family's decrepit yellow Volkswagen bus include put-upon mother Sheryl (Jennifer Laura Thompson); son Dwayne (Taylor Trensch), a teenager who has taken a vow of silence; Richard's father (Mr. Latessa), a reprobate who has been kicked out of his fourth retirement community; and Sheryl's brother, Frank (Malcolm Gets), a Proust scholar who has been de-tenured following a sex scandal involving another Proust scholar (Bradley Dean) and a graduate student (Andrew Samonsky).

The film was a sort of modern day Candide, where the road trip piles disaster upon disaster and father Richard keeps insisting that with a little ingenuity this can still be the best of all possible worlds. The musical substitutes mild satire that mostly comes off as misguided efforts to be cute and a score, by William Finn, full of undistinguished trifles and, for the most part, harmonies and lyrics that are simply not up to standard set by Mr. Finn's previous scores.

There are a couple of exceptions, and each brings to mind a previous success. In act one, Frank runs into the other Proust scholar and the grad student, and Mr. Finn gives them a clever roundelay titled "How Have I Been?" on the sexual politics among three gay men that shimmers with suppressed emotion reminiscent of Falsettoland. In act two, Olive finally gets to display her talent in the pageant with a number coached by Grandpa. This is classic 25th Annual Putnam County Spelling Bee territory, and Mr. Finn responds with "Olive's Moment," which, while nowhere near "Rose's Turn," manages to be clever, raucous and sensitive all at once.

Mr. Lapine's direction tops Mr. Lapine's book by a lot, though I am crediting the really dumb idea of making the ensemble a group of Richard's devotees (which just serves to make everyone involved look foolish) to the book writer, rather than the director. The staging is full of clever touches (including a couple of local gags, one involving a well-known sign along Interstate 5 north of San Diego and the new Arizona immigration law that is actually pretty funny). It is helped along by David Korins' scenic design full of moving objects, including a clever yellow bus that is pushed along by the performers' feet working in close coordination, Ken Billington's colorful and effective lighting, and Dan Moses Schreier's well-tuned sound design. If anything, Jennifer Caprio's costume design could have been even more over-the-top than is the case, though. Christopher Gatelli staged the musical numbers in competent but unexciting fashion.

The cast tends to act like performers in a musical, which turns out to be a mistake. Only Mr. Latessa really registers, though Mr. Gets occasionally is allowed to show what he can do with a song.

Mostly, though, it's a wasted effort. In retrospect, there probably wasn't a musical in Little Miss Sunshine, and it's too bad that it took so much effort and energy to figure that out.

Little Miss Sunshine. Book by James Lapine, music and lyrics by William Finn, musical staging by Christopher Gatelli, and direction by Mr. Lapine. The creative team includes David Korins, scenic designer; Jennifer Caprio, costume designer; Ken Billington, lighting designer; Dan Moses Schreier, sound designer; Vadim Feichtner, music director/conductor; Michael Starobin, orchestrator; and William Aronson: music arranger.